ISLA: That’s right. It’s also an igneous intrusive feature, just like them. The rock they’re made of is called phonolite - also called a ‘sounding stone’, it makes a metallic ...

THE Andean Mountain system in Peru has experienced extensive igneous activity, a significant portion of which was intrusive. A principal feature of this part of the Andes is the coastal batholith ...

Igneous rocks form from the solidification of molten rock material called magma. This process can occur either below the ...